I generally dislike using the set methods to change how the “language” works. So even if it covers my issue, I’m not using it.

If you don’t feel like using it, that’s valid, just as long as you’re aware of the functionality. It seemed fitting here to me because of the potential to simplify the code from a complex chain of commands with hard-coded values to a single command with no hard-coding, while keeping the old behavior.

Also if cd -> rm -rf -> rmdir solves it, why would I need to rewrite and change it to set -u -> rm -rf?

You don’t. You asked for feedback, though, so I gave some.

In general, I’m a fan of set -u because it helps to avoid some common scripting bugs, but if you’re aware of the option and how it could be used, and you choose not to use it, then I’m not going to insist you write it how I would write it.

I think you mistook my asking questions as opposition, or maybe my intent wasn’t clear enough in my comment. My main point was that while I don’t have full context for the problem, it seems to me that a simpler solution exists. Is there some edge case that the cd -> rm -rf -> rmdir snippet covers that’s missed by set -u -> rm -rf?

However, I am very, very afraid of doing rm -rf in context of variables, in case the variable happens to become empty due to user error (or later changes in script).

I get the feeling that either there’s some missing info, a misunderstanding on my part, or there might be a simpler way to do things. Is $TEMPDIR changing a reasonable case to handle? Can you change your script design to make this impossible instead? (Like replacing a source with a script execution?)

If the snippet is just boilerplate at the top of numerous scripts, I’d do set -u, rm -rf "${TEMPDIR}" on exit (ideally defined in a common setup script/function), and just avoid assigning to the var later in the script. In terms of defensive programming, anything extra is added complexity that will only make an error more likely imo. You could rename TEMPDIR to something like TEST_ROOT if you’re concerned about the variable name being accidentally used again, but no amount of trap logic is going to make a future programming error impossible.

Slow depends on the use case. If your main bottlenecks are in code that people have written highly optimized lower-level libraries for, it could be slower to roll your own implementation or use a less mature library in a different language. And in some cases it might not matter if you take 1 ms or 100 ms to do something.

It works the other way too, and you have to weigh the pros and cons of your specific case when you choose a language. What level of abstraction do you want to work at, how stable do you need the toolchain to be, how familiar you are with the language, what’s supported in the language, how easy is it to do what you want, what’s the norm in the domain you’re working in, etc.